Vibratory pile driving apparatus

ABSTRACT

Pile driving apparatus comprises first and second sets of eccentric members mounted in a housing for opposing rotation. A phase shifting arrangement connects the sets of eccentric members for controlling coordinated rotation thereof, and comprises a limiting device between the first and second sets of eccentric members for shifting between a first condition wherein the eccentric members are constrained to rotate out of phase to negate generation of vibration and a second condition wherein the eccentric members are constrained to rotate in phase to generate vibration. Two motors are connected with the limiting device for alternatively driving rotation thereof. A control arrangement selectively drives the limiting device predominantly by the first motor for shifting the limiting device into the first condition thereof for preventing vibration or predominantly by the second motor for shifting the limiting device into the second condition for generating vibration in the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is entitled to the benefit of, and claims priority from, U.S. Provisional Patent Application Ser. No. 61/280,535, filed Nov. 6, 2009, and entitled “Series Motor Resonance-Free System,” the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to vibration systems and methods for driving objects into the earth and, more specifically, to vibration systems that use counter-rotating eccentric members to generate linear vibratory amplitude via centrifugal force.

BACKGROUND OF THE INVENTION

Counter-rotating sets of eccentric members are often used in so-called pile-driving equipment to generate vibratory forces for driving objects into the ground, typically elongate members such as H-beams, sheet piles, caissons, and the like, often collectively referred to as “piles.” The eccentric members used in such equipment may be of any type or shape of rotating element or assembly in which the weighting of the member offsets the center of gravity of the member radially from its axis of rotation. The product of the mass of the eccentric weight of the member times the perpendicular distance of its offset from the rotational axis is referred to as “eccentric moment.”

Such an eccentrically weighted member generates centrifugal force as its offset center of gravity rotates about its axis which thereby produces vibration. As is well-known in the art, when two such eccentrically weighted members of equal eccentric moment are constrained to rotate in synchronism in opposite directions and at equal speed, the opposing centrifugal forces generated by the counter-rotating members will cancel each other in a transverse direction but will be additive, positively or negatively, in a longitudinal direction. The resulting output generates a linear vibration in such longitudinal direction, but essentially no vibration in the transverse direction, and is the basic operating principle of vibratory pile drivers, also known as “vibrodrivers.” Such synchronous opposing rotation is typically accomplished by rotatably connecting the eccentric members via gears, chains, electro-hydraulic control or a similar means. As is also well known in the art, when two pair of eccentric members are arrayed so that the longitudinal axes of the eccentric pairs are aligned and both pairs of eccentric members are constrained to rotate “in-phase” at the same speed and with the identical angular position of the centers of gravity of the eccentric members, the additive longitudinal forces generated by the eccentric members produce a linear sinusoidal vibration. Conversely, when the pairs of eccentric members are rotated “out-of-phase” at an identical speed but with the angular position of their respective centers of gravity offset from one another by 180°, both the longitudinal and transverse force components of each set of eccentric members cancel each other, so that no linear vibration is produced. This is the basic operating principle of vibratory pile drivers.

Such resonance-free vibratory pile driving equipment may employ eccentric members arranged in pairs or alternatively may group eccentric members in sets of a greater number of counter rotating eccentric members, e.g., a set of three eccentric members comprised of one large eccentric member and two smaller eccentric members each having an eccentric moment that is one half that of the larger member. This arrangement is essentially the equivalent of a pair of counter-rotating eccentric members of equal masses.

Known vibratory pile driver constructions include a support frame adapted to be suspended from a crane or a like support and a vibratory assembly mounted to the support frame via elastomeric or similar springs to isolate vibrations from the crane. The vibratory assembly comprises one or more sets of eccentric members for generating linear vibrational forces to drive a pile into the earth and a clamping assembly for selectively clamping and releasing the piles and for transmitting the vibrational forces to said piles while clamped. One or more hydraulic or electric motors are provided for driving rotation of the eccentric members at sufficient speeds, e.g. 1500-2500 rpm, to produce high force, large amplitude vibrations in the vibratory pile driver for driving the piles into the earth.

At start-up, the motor increases the rotational speed of the eccentric members from a standstill to the working speed of the vibratory pile driver. Likewise, when the vibratory pile driver is shut down, the speed of the eccentric members is reduced to a stop. A common problem experienced with known vibratory pile drivers arises during these start-up and shut-down periods. As the speed of the vibratory pile driver increases or decreases through a frequency equal to its natural frequency (i.e., its resonant frequency), potentially destructive vibrations of extreme amplitude can occur that can cause damage to the vibratory pile driver, the pile, the crane and/or possibly adjacent structures such as buildings or the like. Although operators attempt to bring the vibratory pile drivers up to speed and to shut them down as quickly as possible to minimize the amount of damaging vibration that occurs, this practice does not eliminate the risk.

The conventional means for addressing the above-described problems are known vibratory pile driver design variations commonly referred to as variable moment (VM) or resonance free (RF) designs. Both of these designs employ a “phase shifting” arrangement to allow the vibratory pile driver to accelerate to, or decelerate from, operating speed while generating no vibration. By selective phase shifting, vibration output is initiated after the eccentric members have reached operating speed, thus eliminating any period of vibrating at resonant frequencies. An example of a variable moment (VM) vibratory pile driver is described in U.S. Pat. No. 6,604,583, and an example of a resonance free (RF) vibratory pile driver is described in U.S. Pat. No. 7,168,890.

Both variable moment (VM) and resonance free (RF) vibratory pile drivers include a vibratory assembly which comprises at least two sets of multiple eccentric members arranged so that their longitudinal output force components align, producing a uniaxial vibratory force. The eccentric member sets may be arranged concentrically, as represented in U.S. Pat. No. 5,177,386, or horizontally, as represented in U.S. Pat. No. 7,168,890, but are most commonly arranged vertically, as represented in U.S. Pat. No. 6,604,583, i.e., with a top row of eccentric members positioned directly above a bottom row of eccentric members. Typically, the top row and bottom row of eccentric members are each driven by independent hydraulic motors, although any number of motors may be used depending on the size of the vibratory pile driver and other design criteria of the unit. The top and bottom eccentric members are connected and synchronized by the aforementioned phase shifting arrangement, which is capable of adjusting the relative angular relationship of the top and bottom eccentric members from 0°, or “in phase” with each other, to 180°, or “out of phase” with each other. Depending upon the type of phase shifting arrangement utilized, the top set of eccentric members and the bottom set of eccentric members may rotate in the same direction or in opposite directions. Many types of phase shifting arrangements are known and used in these vibratory pile drivers, and include bevel gear sets, harmonic gear sets, planetary gear sets, swinging spur gear sets, helical splines, helical cams, differential motor displacement, hydraulic rotary actuators and the like. In the forgoing types of phase shifting devices, some are self limiting to produce only a maximum of 180° relative movement, while others require additional limiting mechanisms (e.g., stops or a stop mechanism) to limit the phase shift to 180°.

In the case of a variable moment (VM) vibratory pile driver, the phase shifting device has the ability to adjust infinitely the phase relationship of the top eccentric members to the bottom eccentric members between 0° and 180° and to hold the relationship setting while the vibratory pile driver is running. Thus, the overall effective eccentric moment of the machine is infinitely adjustable between a zero value and a maximum value.

In the known types of resonance free (RF) vibratory pile drivers, the phase shifting mechanism is only capable of setting the phase relationship of the top eccentric members and the bottom eccentric members at two positions, i.e. 0° in phase and 180° out of phase. Consequently, the overall effective eccentric moment of the machine is either a zero value or a maximum value.

Both the variable moment (VM) and the resonance free (RF) types of vibratory pile drivers solve the low speed resonance problems described above. On one hand, the additional ability of variable moment (VM) vibratory pile drivers to permit infinite eccentric moment adjustment would seem to be an advantage. On the other hand, however, this infinitely adjustable feature is seldom used since maximum eccentric moment will almost always drive piles faster than a lesser moment. Further, all the known applicable phase shifting arrangements used in variable moment (VM) pile drivers are extremely expensive and fairly complicated. This adverse effect on the overall cost of a variable moment (VM) vibratory pile drivers essentially means that they cannot be justified except in extremely high risk areas or very sensitive job sites. It is also well known that these infinitely variable phase shifters are often unreliable, due to the vibrating environment and the relative small space into which they must fit.

The resonance free (RF) type of vibratory pile driver tends to be less complex, with resultant lower cost. However, the known phase shifting arrangements which produce the resonance free (RF) type of functionality have little or no control of the shifting speed and rely on mechanical stops to limit the maximum phase shift angular displacement. Due to the heavy masses being phase shifted, and the violent, high velocity impacts of the stop mechanism, these phase shifting arrangements are also unreliable.

SUMMARY OF THE INVENTION

The present invention seeks to address the disadvantages and problems of known phase shifting arrangements in vibratory pile drivers. Basically, the present invention provides an apparatus for driving an object into the ground and for removing an object from the ground by imparting to the object vibration generated via rotation of eccentric members, comprising a housing, a first set of eccentric members mounted in the housing for synchronized rotation in opposing directions relative to one another, and a second set of eccentric members mounted in the housing for synchronized rotation in opposing directions relative to one another, with the first and second sets of eccentric members being disposed relative to one another (e.g., vertically or horizontally with respect to one another) to generate vibrational force in the housing in a common longitudinal direction.

The apparatus further includes a phase shifting arrangement connecting the first and second sets of eccentric members for controlling coordinated rotation thereof. More specifically, the phase shifting arrangement comprises a limiting device arranged between the first and second sets of eccentric members to be shiftable between a first condition wherein the first and second sets of eccentric members are constrained to rotate out of phase with one another to negate generation of vibration in the housing and a second condition wherein the first and second sets of eccentric members are constrained to rotate in phase with one another to generate vibration in the housing. According to the present invention, each of a first motor and a second motor is independently connected with the limiting device for driving rotation thereof. A control arrangement is provided for selectively driving the limiting device predominantly by the first motor for shifting the limiting device into the first condition thereof for maintaining the first and second sets of eccentric members in the first non-vibrating condition or for selectively driving the limiting device predominantly by the second motor for shifting the limiting device into the second condition for generating vibration in the housing.

In a preferred embodiment of the invention, the first set of eccentric members may comprise a first pair of eccentric members, and likewise the second set of eccentric members may comprise a second pair of eccentric members. The limiting device preferably comprises first and second drive components which are shiftable relative to one another between the first and second conditions. The first motor is preferably a hydraulic motor connected with the first drive component of the limiting device for driving rotation thereof, and similarly the second motor is preferably a hydraulic motor connected with the second drive component of the limiting device for driving rotation thereof.

In a preferred embodiment, the phase shifting arrangement further comprises a first hydraulic circuit connecting the first and second motors in hydraulic series for delivering a first source of pressurized hydraulic driving fluid to the first and second motors in sequence. The control arrangement preferably comprises a second hydraulic circuit including a second source of pressurized hydraulic driving fluid. The second hydraulic circuit is connected to the first hydraulic circuit and the control arrangement further comprises a control device for selectively adding supplementary hydraulic fluid to and withdrawing hydraulic fluid from the first hydraulic circuit to selectively shift the limiting device between the first and second conditions thereof. Preferably, the first condition of the limiting device is utilized for maintaining the first and second sets of eccentric members in the first non-vibrating condition during start-up acceleration and shut-down deceleration thereof and the second condition of the limiting device is utilized to generate vibration in the housing when the first and second sets of eccentric members are rotating at an operating speed. The control device may comprise a solenoid valve movable between a position wherein the second source of pressurized hydraulic driving fluid delivers the hydraulic fluid to the first hydraulic circuit and a position for receiving hydraulic fluid from the first hydraulic circuit.

In a preferred embodiment, the first drive component of the limiting device may comprise a first pinion connected with the first set of eccentric members for driving rotation thereof and the second drive component of the limiting device may similarly comprise a second pinion connected with the second set of eccentric members for driving rotation thereof. The first and second pinions are mounted for relative rotation about a common axis and have respective stop surfaces arranged to shift between engagement in a first abutting relationship in the first condition and in a second abutting relationship in the second condition, thereby to limit relative rotation between the first and second conditions.

It is preferred that the first and second motors are equivalent and each motor is independently capable of driving the phase shifting arrangement. The eccentric members are preferably identical to one another. In a preferred embodiment, the first and second sets of eccentric members are arranged with one set vertically above and in alignment with the other set.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a representative arrangement of a pair of eccentric members, illustrating the basic principle of operation of prior art vibratory pile driving apparatus;

FIGS. 2 and 3 are schematic views similar to FIG. 1 showing alternative representative prior art arrangements of eccentric members;

FIG. 4 is a schematic side view of a prior art vibratory pile driving apparatus, showing the eccentric members thereof rotating in phase with one another;

FIG. 5 is a vertical cross-sectional view of the prior art pile driving apparatus of FIG. 1, taken along line V-V thereof;

FIG. 6 is another side view of the prior art apparatus of FIGS. 4 and 5, showing the eccentric members thereof rotating out of phase with one another;

FIG. 7 is a schematic isometric view of a vibratory pile driving apparatus according to one preferred embodiment of the present invention, depicting the eccentric members thereof rotating in phase with one another;

FIG. 8 is a schematic isometric view of the vibratory pile driving apparatus of FIG. 7, depicting the eccentric members thereof rotating out of phase with one another;

FIG. 9 is a schematic isometric view of a vibratory pile driving apparatus according to a second preferred embodiment of the present invention;

FIG. 10 is a schematic isometric view of a vibratory pile driving apparatus according to a third preferred embodiment of the present invention;

FIG. 11 is a schematic isometric view of an alternative embodiment of synchronizing arrangement for a vibratory pile driving apparatus according to the present invention;

FIGS. 12A-12D are schematic isometric views of the synchronizing arrangement of FIG. 11, depicting differing operational conditions thereof; and

FIG. 13A-13D are schematic vertical cross-sectional views of the synchronizing arrangement of FIG. 11, corresponding to the conditions of FIGS. 12A-12D, respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the accompanying drawings, FIGS. 1-6 depict schematically the above-described principle of operation of known vibratory pile driving apparatus wherein counter-rotating eccentric members are utilized to vibrationally generate rectilinear motion that can be transmitted to a pile or other object to be driven into the earth. Basically, such eccentric members can be substantially any form of rotating element or assembly in which the weight distribution of the member offsets its center of gravity from its axis of rotation, as representatively depicted in FIG. 4 wherein each rotating member has a center of gravity spaced by the indicated radial offset from the axis of rotation of the member. Such an eccentrically weighted member generates centrifugal force as its offset center of gravity rotates about the axis which thereby produces vibration.

FIGS. 1-3 depict the basic principles of operation of vibratory pile drivers as described above. Specifically, FIG. 1 illustrates a single pair of synchronously counter-rotating eccentric members showing their centers of gravity and corresponding centrifugal force output vectors at four differing positions of rotation. Each of FIGS. 2 and 3 similarly illustrate four differing rotational positions of vibratory arrangements wherein eccentric members are grouped in sets of three counter rotating eccentric members comprised of one large eccentric member and two smaller eccentric members each having an eccentric moment that is one half that of the larger member, arranged horizontally with respect to one another as depicted in FIG. 2, or vertically with respect to one another, as depicted in FIG. 3.

FIGS. 4-6 depict one known prior art vibratory pile driving apparatus of the type disclosed in European Patent Document EP-A-0524056, as further described in U.S. Pat. No. 6,604,583. In such apparatus, a first pair of eccentric weights 1, 2 are rotatably disposed vertically above a second pair of rotatable eccentric members 3, 4 within a housing 14 adapted to be clamped or otherwise affixed to an object (such as a pile, not shown) to be vibrationally driven. Each of the eccentric weights 1, 2, 3, 4 is mounted on a respective gear 5, 6, 7, 8, with the gears 5, 6 and 7, 8 of each respective pair of weights in meshing engagement with each other, whereby the weights 1, 2, 3, 4 of each pair rotate in opposite directions as indicated by directional arrows. Each pair of eccentric weights is driven via a respective hydraulic motor 9, 10 disposed in mesh with a respective gear 5, 7 of the eccentric weight 1, 3. Gears 6, 8 supporting eccentric weights 2, 4 are each in mesh with respective gears 11, 12 mounted on a shaft 15 of a differential type of phase shifter 13 which is operative to shift the eccentric weights 1, 2 relative to the eccentric weights 3, 4 between an in-phase orientation depicted in FIG. 1, causing the weights to vibrate rectilinearly in a vertical direction, i.e., from top to bottom as viewed in FIG. 1, and an out-of-phase orientation depicted in FIG. 3, wherein the pairs of eccentric weights 1, 2 and 3, 4 cancel the vibratory force of the other thereby attenuating any vibration of the apparatus.

With reference now to FIGS. 7 and 8, a vibratory pile driving apparatus according to the present invention is schematically depicted in one embodiment of a simple, rugged, reliable and inexpensive design functional as a resonance free (RF) type of apparatus. In this embodiment, the apparatus only provides minimum and maximum eccentric moment adjustment positions, as is characteristic of resonance-free (RF) apparatus. The vibratory pile driver structure of FIG. 7 comprises two pairs of eccentric members 20, 21 and 22, 23, respectively, mounted in a common vertically arrayed layout (e.g., as in FIGS. 1-3) for counter-rotation (e.g., via coaxial intermeshing gears, not shown) with one pair vertically above the other within a housing (also not shown), which may be of any suitable structure and configuration adapted to be suspended via a crane or other support structure for operation to drive piles or like objects.

A phase shifting arrangement, indicated overall at 24, connects the two pairs of eccentric members 20, 21, 22, 23 to control coordinated rotation of the members, and includes a limiting device in the form of a double pinion mechanism 26 comprised of two pinion gears 28, 29 mounted coaxially with one another and in meshing engagement respectively with the gears of eccentric members 20, 22. The pinions 28, 29 are independently rotatable except that each pinion 28, 29 includes a stop 28A, 29A, respectively, projecting axially toward each other for engagement whenever one pinion rotates substantially a full revolution in either direction relative to the other pinion, thereby to limit the amount of relative rotation of the pinions. The gear ratios of the eccentric members 20, 21, 22, 23 and the pinions 28, 29 and the respective centers of gravity of the eccentric members are arranged such that, when the pinions 28, 29 are rotated in respective clockwise directions into a first condition wherein their stops 28A, 29A abut, the two pairs of eccentric members are disposed out of phase with one another to negate generation of vibration in the housing, as depicted in FIG. 8, and when the pinions 28, 29 are rotated in respective counterclockwise directions into a second condition into abutment of their stops 28A, 29A, the two pairs of eccentric members are disposed in phase with one another for generating vibration in the housing, as depicted in FIG. 7. Each pinion 28, 29 is driven independently via a respective motor 30, 31, preferably a hydraulic motor.

According to the present invention, the two hydraulic motors 30, 31 are driven from a hydraulic power unit, such as a pump 32, via a hydraulic circuit 34 in which the motors 30, 31 are arranged in series to receive pressurized hydraulic fluid in sequence first to the motor 30 and then to the motor 31. The hydraulic motors 30, 31 are of equal power displacement selected such that either motor is sufficiently powered to alone drive the overall pile driving apparatus, but because the motors 30, 31 are plumbed together in series, the motors only develop the torque of a single motor and only rotate at the same speed as a single motor. As will be understood, if the pinions 28, 29 did not include stops 28A, 29A, the motors 30, 31 would rotate at approximately the same speed, but with nothing to control their particular phase relationship. Also, as will be understood, the fluid pressure in the intermediate section 34A of the hydraulic circuit 34 between the exhaust port A of motor 30, and the intake port A of motor 31, will be about half that applied at the intake B to pump 30.

According to a unique feature of the current invention, a second hydraulic circuit 36 supplied with pressurized hydraulic fluid from an independent pump or other hydraulic power unit 38 is connected in fluid communication with the intermediate section 34A of the hydraulic circuit 34 between the two motors 30, 31. The hydraulic circuit 36 is controlled via a solenoid valve 40 to operate to selectively add or subtract small amounts of hydraulic fluid flow to or from the intermediate section 34A of the hydraulic circuit 34. When vibration is desired in the apparatus, the solenoid valve 40 is deenergized to move into the position shown in FIG. 7 to disconnect the hydraulic circuit 36 from the pump 38, thereby relieving pressure within the circuit 36 and allowing a small flow of hydraulic fluid to flow from the hydraulic circuit 34 into the circuit 36. The motors 30, 31 are constrained to rotate at the same speed by engagement of the pinion stops 28A, 29A, and accordingly this diverted fluid flow causes the pressure in the circuit section 34A and the pressure at the intake port A of the motor 31 to reduce to a sufficiently low level that the motor 31 ceases to apply driving torque to the pinion 29 and the motor 30 begins to drive both the bottom pair of eccentric members 22, 23 and the top pair of eccentric members 20, 21 via the pinions 28, 29.

When it is desired to prevent vibration in the apparatus, the solenoid valve 40 is energized to move into the position shown in FIG. 8 to connect the pump 38 to the hydraulic circuit 36, whereby the pressurization of the circuit 36 directs a small controlled flow of hydraulic fluid from the pump 38 into the hydraulic circuit 34. The hydraulic pressure in the section 34A of the circuit 34 thereby increases such that, when the pressure prevailing in the circuit section 34A exceeds the system pressure at the pump 32, the continuing fluid flow from the circuit 36 into the circuit section 34A causes the two motors 30, 31 to slowly rotate in opposite relative directions from one another, which in turn causes the top pair of eccentric members 20, 21 and the bottom pair of eccentric members 22, 23 to slowly rotate toward their out-of-phase disposition. This relative opposing rotation of the eccentric members occurs whether the apparatus is stopped or is running at full speed. When the respective stops 28A, 29A of the pinions 28, 29 contact each other due to their opposite rotation, the eccentric members 20, 21, 22, 23 are 180 degrees out of phase. Opposite rotation of the pinions ceases and both motors 30, 31 are again constrained to rotate at the same speed. At this point, the hydraulic pressure is the same at both the intake and exhaust ports A, 13 of the motor 30, whereupon the motor 30 ceases to generate torque. Full system pressure prevails at the intake port A of the motor 31 such that the motor 31 begins to drive both the top and bottom pairs of eccentric members in their phase shifted position via the engaged pinions 28, 29. Thus, since only one of the motors 30, 31 drives the vibratory pile driving apparatus whether its eccentric members are in phase or out of phase with one another, and since half the torque in the system is transmitted through the pinion stops 28A, 29A, the stops are sure to be in contact, with force applied, during continuous operation.

The rate of fluid flow into and from the hydraulic circuit 34 via the circuit 36 is regulated via two pressure compensated flow control valves and ball checks, indicated overall at 42, regardless of the pressure prevailing in the two circuits. The amount and rate of flow must be accurately controlled to prevent the motors 30, 31 from driving the pinions 28, 29 too rapidly between the positions of FIGS. 7 and 8, which risks potentially violent rotational impact between the stops 28A, 29A of the pinions 28, 29. Similarly, it is equally important to provide a sufficient fluid flow to the motor 31 in the condition of FIG. 7 to prevent cavitation of the motor.

Although the above description of operation for the current invention relates to a vibratory pile driver apparatus in which sets of eccentric members are vertically arrayed, the principles of the present invention apply equally well to apparatus having horizontally arrayed eccentric members and to apparatus having concentrically arranged eccentric members. Fundamentally, it is merely important that the sets of eccentric members be disposed relative to one another to be capable of generating vibrational force in the housing in a common uniaxial direction when the eccentric members are rotated in phase with each other. Persons skilled in the art will also recognize and understand that embodiments with a greater number of pairs of eccentric members or with more than two eccentric members in each set are equally possible. Likewise, a greater number of hydraulic motors may be utilized, and may be differently arranged, e.g., at the same side of the apparatus.

For example, FIG. 9 depicts an alternative embodiment of the present invention wherein both motors 30, 31 are disposed on the same side of the limiting device, which in this embodiment is accomplished by the provision of another pinion 129 disposed on the opposite side of the top pair of eccentric members 20, 21 in meshing engagement with the eccentric member 21 to be driven by the motor 31 from the same side of the apparatus as the motor 30.

FIG. 10 depicts another embodiment of the present invention utilizing additional hydraulic motors to drive the vibratory apparatus to accommodate a much larger eccentric moment than is economically or physically feasible with only two larger motors arranged as in the embodiments of FIGS. 7-9. In this embodiment, two reasonable sized motors 30, 31 are used to perform the phase shifting function in conjunction with the double pinion arrangement 28, 29, as well as to apply some power to the rotating system. Two additional motors 130, 131 are mounted and connected to the system via two additional pinion gears 128, 129, and are supplied with operating hydraulic fluid via an additional hydraulic circuit 134. In such arrangement, the additional motors 130, 131 and pinions 128, 129 have no phase shifting function and act only to add driving power to the apparatus, the motor 131 driving the top pair of eccentric members 20, 21 and the motor 130 driving the bottom pair of eccentric members 22, 23. As many additional pairs of motors and pinions may be installed as necessary or desirable to achieve a required or desired power input for any given vibratory pile driving apparatus.

As will be understood, each of the embodiments of the present invention thus far described is of the resonance free (RF) type of vibratory pile driving apparatus. The present invention however is not limited to such resonance free (RF) embodiments. FIGS. 11, 12A-12D and 13A-13D depict another possible embodiment of the present invention utilizing a modified form of double pinion mechanism 228, 229 wherein each pinion 228, 229 is formed with two axial levels of stops which permit the pinions to be selectively engaged in each of 0° in-phase engagement with each other (FIGS. 12A, 13A), 180° out of phase engagement with each other (FIGS. 12B, 13B), and intermediate selectable positions therebetween (FIGS. 12C,13C, and 12D, 13D). More specifically, as best seen in FIG. 11, each synchronizing pinion gear 228, 229 has a stop surface 228B, 229B projecting axially from the main body of the pinion gear and spanning approximately 210° about the gear, with stops 228A, 229A (corresponding to the stops 28A, 29A of FIGS. 7-9) projecting axially from the stops 22813, 229B. The stops 228A, 229A function identically to the stops 28A, 29A in the embodiments of FIGS. 7-9 to limit relative rotation of the top and bottom pairs of eccentric members to the maximum out-of-phase and the minimum in-phase eccentric moment positions represented in FIGS. 12A, 13A and 12B, 13B. The shaft on which the pinion 229 is mounted is connected via a thrust bearing 250 to be axially shiftable toward and away from the pinion 228 via a double acting hydraulic cylinder assembly 252. Thus, when an intermediate eccentric moment is desired, the pinion 229 may be moved axially toward the pinion 228 to dispose the stop 229A within the recessed area within the stop surface 228B of pinion 228, whereby relative rotation of the pinions 228, 229 is further restricted between two intermediate dispositions wherein the stop 228A abuts opposite sides of the stop 229B, as depicted in FIGS. 12C, 13C and 12D, 13D. The circumferential extent of the stops 228B, 229B may be selectively set to achieve any desired intermediate level of eccentric moment, e.g., 30% and 60% eccentric moments as represented in FIGS. 12C, 13C and 12D, 13D.

As will thus be understood, the vibratory pile driving apparatus of the present invention advantageously provides a simplified design, as compared to known prior art apparatus, which is rugged, reliable and inexpensive as well as being adapted to function in differing embodiments as a resonance free (RF) type of pile driving apparatus and as a variable moment (VM) type of pile driving apparatus with selectively fixed intermediate positions.

Those persons skilled in the art will thus recognize and understand that the invention is susceptible of broader utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, it is to be understood that the foregoing disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof. 

1. Apparatus for driving an object into the ground and for removing an object from the ground by imparting to the object longitudinal vibration generated via rotation of a plurality of eccentric members, the apparatus comprising: (a) a housing, (b) a first set of eccentric members mounted in the housing for synchronized rotation in opposing directions relative to one another, (c) a second set of eccentric members mounted in the housing for synchronized rotation in opposing directions relative to one another, (d) the first and second sets of eccentric members being disposed relative to one another to generate vibrational force in the housing in a common longitudinal direction, and (e) a phase shifting arrangement connecting the first and second sets of eccentric members for controlling coordinated rotation thereof, the phase shifting arrangement comprising: (i) a limiting device arranged between the first and second sets of eccentric members, (ii) the limiting device being shiftable between a first condition wherein the first and second sets of eccentric members are constrained to rotate out of phase with one another to negate generation of vibration in the housing and a second condition wherein the first and second sets of eccentric members are constrained to rotate in phase with one another to generate vibration in the housing, (iii) a first motor connected with the limiting device for driving rotation thereof, (iv) a second motor connected with the limiting device for driving rotation thereof, and (v) a control arrangement for selectively driving the shift-limiting device predominantly by the first motor for shifting the limiting device into the first condition thereof for maintaining the first and second sets of eccentric members in the first non-vibrating condition and for selectively driving the limiting device predominantly by the second motor for shifting the limiting device into the second condition for generating vibration in the housing.
 2. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 1, wherein the first set of eccentric members comprises a first pair of eccentric members.
 3. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 1, wherein the second set of eccentric members comprises a second pair of eccentric members.
 4. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 1, wherein the limiting device comprising first and second drive components which are shiftable relative to one another between the first and second conditions.
 5. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 4, wherein the first motor is a hydraulic motor connected with the first drive component of the limiting device for driving rotation thereof.
 6. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 5, wherein the second motor is a hydraulic motor connected with the second drive component of the limiting device for driving rotation thereof.
 7. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 6, wherein the phase shifting arrangement further comprises a first hydraulic circuit connecting the first and second motors in hydraulic series for delivering a first source of pressurized hydraulic driving fluid to the first and second motors in sequence.
 8. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 7, wherein the control arrangement comprises a second hydraulic circuit including a second source of pressurized hydraulic driving fluid.
 9. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 8, wherein the second hydraulic circuit is connected to the first hydraulic circuit and wherein the control arrangement further comprises a control device for selectively adding supplementary hydraulic fluid to and withdrawing hydraulic fluid from the first hydraulic circuit to selectively shift the limiting device between the first and second conditions thereof.
 10. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 9, wherein the control device comprises a solenoid valve movable between a position wherein the second source of pressurized hydraulic driving fluid delivers the hydraulic fluid to the first hydraulic circuit and a position for receiving hydraulic fluid from the first hydraulic circuit.
 11. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 4, wherein the first drive component of the limiting device comprises a first pinion connected with the first set of eccentric members for driving rotation thereof and the second drive component of the limiting device comprises a second pinion connected with the second set of eccentric members for driving rotation thereof, the first and second pinions being mounted for relative rotation about a common axis and having respective stop surfaces arranged for abutment to limit relative rotation between the first and second conditions.
 12. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 1, wherein the first and second motors are equivalent and each motor is capable of driving the phase shifting arrangement and the eccentric members.
 13. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 1, wherein first and second sets of eccentric members are arranged with one set vertically above and in alignment with the other set.
 14. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 1, wherein the eccentric members are identical to one another.
 15. Apparatus for driving an object into the ground and for removing an object from the ground by imparting to the object vibration generated via rotation of eccentric members, the apparatus comprising: (a) a housing, (b) a first set of eccentric members mounted in the housing for synchronized rotation in opposing directions relative to one another, (c) a second set of eccentric members mounted in the housing for synchronized rotation in opposing directions relative to one another, (d) the first and second sets of eccentric members being disposed relative to one another to generate vibrational force in the housing along a common longitudinal direction, and (e) a phase shifting arrangement connecting the first and second sets of eccentric members for controlling coordinated rotation thereof, (f) the phase shifting arrangement comprising (i) a limiting device arranged between the first and second sets of eccentric members, (ii) the limiting device comprising first and second drive components which are shiftable relative to one another between a first condition wherein the first and second sets of eccentric members are constrained to rotate out of phase with one another to negate generation of vibration in the housing and a second condition wherein the first and second sets of eccentric members are constrained to rotate in phase with one another to generate vibration in the housing, (iii) a first hydraulic motor connected with the first drive component of the limiting device for driving rotation thereof, (iv) a second hydraulic motor connected with the second drive component of the limiting device for driving rotation thereof, (v) a first hydraulic circuit connecting the first and second motors in hydraulic series for delivering a first source of pressurized hydraulic driving fluid to the first and second motors in sequence, (vi) a second hydraulic circuit including a second source of pressurized hydraulic driving fluid, (vii) the second hydraulic circuit being connected to the first hydraulic circuit and including a control device for selectively adding supplementary hydraulic fluid to and withdrawing hydraulic fluid from the first hydraulic circuit to selectively shift the limiting device between the first condition thereof for maintaining the first and second sets of eccentric members in the first non-vibrating condition during start-up acceleration and shut-down deceleration thereof and the second condition for generating vibration in the housing when the first and second sets of eccentric members are rotating at an operating speed.
 16. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 15, wherein the first drive component of the limiting device comprises a first pinion connected with the first set of eccentric members for driving rotation thereof and the second drive component of the limiting device comprises a second pinion connected with the second set of eccentric members for driving rotation thereof, the first and second pinions being mounted for relative rotation about a common axis and having respective stop surfaces arranged for abutment to limit relative rotation between the first and second conditions.
 17. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 15, wherein the control device comprises a solenoid valve movable between a position wherein the second source of pressurized hydraulic driving fluid delivers the hydraulic fluid to the first hydraulic circuit and a position for receiving hydraulic fluid from the first hydraulic circuit.
 18. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 15, wherein the first and second hydraulic motors are equivalent and each motor is capable of driving the phase shifting arrangement.
 19. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 15, wherein first and second sets of eccentric members are arranged with one set vertically above and in alignment with the other set.
 20. Apparatus for driving an object into the ground and for removing an object from the ground according to claim 15, wherein the eccentric members are identical to one another. 